Abstract
This study investigated the protective properties of fecal microbiota derived from mice treated with sodium alginate (SA) and normal mice with both types immunosuppressed by exposure to antibiotics and cyclophosphamide. A dietary intervention using SA obviously increased the diversity and improved the composition of gut microbiota in normal mice. Fecal microbiota transfer (FMT) from both mice treated with sodium alginate and normal mice alleviated spleen tissue damage and improved immune function. FMT alleviated intestinal mucosal injury and reduced intestinal permeability via increasing mucin and tight junction protein expression. In addition, FMT reduced gut inflammation via down-regulating the expression of toll-like receptor 4 protein. Furthermore, FMT treatment improved the disordered gut microbiota via increasing the abundance of Lactobacillus and Lachnospiraceae NK4A136 group whilst decreasing the abundance of Bacteroides. PICRUSt2 function prediction analysis showed that, compared with the model group, FMT treatment significantly down-regulated lipopolysaccharide biosynthesis and the mitogen-activated protein kinase signaling pathway-fly. Collectively, we found that SA can regulate the gut microbiota structure of normal mice and confirms the effectiveness of FMT in alleviating intestinal barrier damage and gut dysbiosis in antibiotic-cyclophosphamide-induced immunosuppressed mice. This work also reveals that SA can potentially alleviate the immunosuppression caused by cyclophosphamide in mice by modulating the intestinal microbiota and exploiting their functional properties.